effective

The word “effective” means producing the intended result; actually working. In plain terms, something that works, gets the job done, or (for rules/dates) officially starts applying.

“Effective” is pronounced ih-FEHK-tihv (/ɪˈfɛktɪv/ in IPA).

Here is “effective” used in a sentence: “The new medication proved effective against the infection.”

“Effective” is an adjective.

The word “effective” comes from Latin. From French effectif, based on Latin efficere, "to bring about" or "accomplish" — the same root that gives us "effect" and "efficient.".

“Effective” is a very common word in modern English, usually learned at around the B1 level.

“Effective” has 2 distinct senses listed in this dictionary. The most common is: producing the intended result; actually working.

Effective means producing the intended result — it works. Efficient means producing that result with little wasted time, effort, or money. A method can be effective but inefficient, like heating a room by leaving the oven on: it warms the place, yet it wastes energy. Efficiency is about how economically you succeed.

Though they sound alike, the meanings differ. Effective means working or producing the intended result. Affective is a more technical word relating to moods, feelings, and emotions, as in 'affective disorders.' If you mean that something succeeds or works, the word you want is almost always effective.

The direct opposite is ineffective — failing to produce the intended result. Related antonyms include useless, fruitless, and unproductive. Where effective marks something that works and achieves its aim, these words describe efforts that fall short and leave the goal unmet.

You might say, 'The new policy was highly effective at cutting waiting times,' or 'a simple but effective solution.' In each case the thing described actually achieves what it set out to do — the test of whether something is effective is results, not effort or intention.